Knee braces are known in the prior art. The movement of the knee joint is limited in certain cases, but in almost every instance the braced knee is permitted some movement. The knee-joint is made up of two condyloid joints and a third joint, partly arthrodial, but not completely, since the articular surfaces are not mutually adapted to each other. The resulting movement is not a simple gliding motion. The principle movements that take place at the knee joint are flexion and extension.
The movements of flexion and extension at this joint differ from those in a typical hinged joint, such as the elbow or hip. The axis around which motion takes place in the knee joint is not fixed, but the axis shifts forward during extension, as the gliding movement is superimposed on the rolling motion and the axis shifts backward during flexion.
Although the knee joint has been described as a hinged joint in the prior literature; it has a more complicated character. The knee joint must be regarded as consisting of three articulations, of two different kinds. The first is a condyloid articulation; in this form of the joint, an ovoid articular surface, or condyle, is received into an elliptical cavity in such a manner as to permit flexion, extension, abduction, adduction, and circumduction, but no axial rotation. The second kind of articulation involved is arthrodial; this is a joint which permits only gliding movement. It is formed by the apposition of plane surfaces, or one slightly concave, the other slightly convex. The amount of motion between these surfaces is limited by the ligaments or osseous processes surrounding the articulation.
When damage or injury occurs to the knee joint some form of suitable bracing is required. Associated with the bracing, in order to permit movement, as flexion and extension of the knee joint, there is a hinged structure pivotal about the knee joint.
Previous known knee braces and protective devices contain simple hinged structures or more recently a biaxial hinge. All of the previously designed hinges attempted to parallel the complex movement of the knee joint. Some knee braces for support and protection of the knee joint incorporate both an inner and an outer bracing structure.
Anderson, U.S. Pat. No. 4,249,524, discloses a true biaxial or double hinged pivotal brace and knee stabilizer. McDavid, U.S. Pat. No. 3,528,412, describes a brace with a fixed single pivot hinge. Rigdon, U.S. Pat. No. 4,219,892, discloses a knee brace having an accordian-folded section filled with fluid and held together with tension straps.
French Patent Application No. 79-10960 discloses a "link" hinge. The intermediate link has a longitudinal slot, the slot allows one of the uprights to move only in the direction of the longitudinal axis. The other end of the link has a fixed pivot to which is connected the other upright or brace extension. Canadian Pat. No. 1,011,204 relates to a knee brace with a dual planer link element between the elongated upper and lower arms of the brace. The arm and connecting link are essentially planer and are limited in pivotal motion to the plane of the link element and the front and back stops of the link element has an upper and lower pivot points spaced apart by a distance range of about 3/4 of an inch to about 2 inches.
Frank, U.S. Pat. No. 4,340,041, relates to an articulate splint having upper and lower anchor bars connected to a lock plate. The lock plate contains a hinge means. The hinge means in the lock plate has a single pivotal axis. Taylor, U.S. Pat. No. 3,902,482, describes a mechanical joint for orthopedic braces or prosthesis. The joint has an upper and lower portion attached by a link. Each portion has dual bearings which combine to provide a pivotal movement closely simulating the flexing action of a knee.
Meany, U.S. Pat. No. 2,460,895, relates to a joint protector having a longitudinally movable hinged joint; one fixed pivotal end, and one pivotal and longitudinally sliding connection. Goodwin, U.S. Pat. No. 58,403, relates to a surgical splint with a movable hinge having a set-screw moving in a slot and a single fixed pivot. Barry, U.S. Pat. No. 1,374,177, relates to an orthopedic appliance having a free pivotal connection and a means for fixing the connection so as to form a rigid structure. There is no provision for movement.
Rossman, U.S. Pat. No. 3,581,741, relates to a partially leg encircling knee brace with a hinge means on the upper inside body portion which includes a single rivet and a single pivot pin or rivet connecting a bar between the upper hinge and the lower body portion of the brace. Clegg, U.S. Pat. No. 901,592, relates to bracing device with a single pivot in conjunction with slide button in the slot which together allow vertical movement as well as single point pivot. Peckham, U.S. Pat. No. 2,467,907, describes a knee brace having springs pivotally attached top and bottom to two centrally disposed shaped plates on the inside and outside of the knee joint. In effect each pivot point is a rotary pivot at a single point. Peckham, U.S. Pat. No. 3,194,233, relates to a corrective and protective knee brace which has a pair of curved pressure members on opposite sides of the knee joint. The curved pressure members contain hinge joints which are made up of conventional hinge parts.
McClure, U.S. Pat. No. 3,350,719, relates to a knee brace having an upper bar and a lower bar which are pivotally joined with a hinge arrangement. The hinge in McClure is a link bar with an upper pivot pin and a lower pivot pin. The pivot pin provides a double conventional pivoting hinge joint connecting the upper brace bar and the lower brace bar through the link bar.
Each of the prior art hinges associated with the knee braces or protective devices, includes a simple pivoting hinge, either alone as a single pivot point or a pair of single pivot points spaced apart or in close proximity. All of the prior braces attempt to provide a hinge device to emulate and move parallel to the complex movement of the knee joint. Some braces are in place when the leg is extended, but fail to accurately follow the knee motion when flexed.